When Georgia Tech’s unorthodox flexbone option offense threw a surprise attack at the University of Miami football team, defensive coordinator Mark D’Onofrio had to tear up a page of his gameplan, scribble a new one and teach it to his players on the fly.

When Georgia Tech’s unorthodox flexbone option offense threw a surprise attack at the University of Miami football team, defensive coordinator Mark D’Onofrio had to tear up a page of his gameplan, scribble a new one and teach it to his players on the fly.

UM’s defense, facing its first true test of the season, was cramming on the sideline.

To make the crisis worse, UM’s offense could not stay on the field for more than a fleeting one minute and 59 seconds in the first quarter, forcing the breathless defense to keep sprinting back into action against Tech’s waves of running backs.

Despite the chaos, UM’s defense didn’t panic, made adaptations and captured the pivotal plays of the fourth quarter to keep UM undefeated with a 45-30 victory in its Atlantic Coast Conference opener on Saturday.

Last season, UM’s offense usually had the chore of rescuing the worst defense in school history. But against Georgia Tech, UM’s defense continued its rapid rise to respectability by bailing out the offense, which turned the ball over four times.

D’Onofrio and his defense, maligned and mocked for two years, squirted out from under the microscope in UM’s first comeback of the season. In the final seven minutes, Ladarius Gunter, Shayon Green, Rayshawn Jenkins, Tyriq McCord, Denzel Perryman, Anthony Chickillo and their unit mates burst the seams on a tight score. Interceptions led — indirectly and directly — to two of UM’s last three touchdowns.

It’s just the sort of resourcefulness No. 14 UM needs if it hopes to get to the ACC championship game and buttress its return to Top 25 territory.

Stephen Morris has established his ability to reach into his deep and loaded quiver. No one frets about the offense’s skill at scoring quickly and regularly.

Silencing doubters

But in four games against only one worthy opponent, doubts still remained about the defense, which was ranked among the FBS dregs last year. D’Onofrio and coach Al Golden kept saying that inexperience was the problem.

So, in year three of the Golden era, has the defense really grown up?

The Georgia Tech win provided solid evidence, especially since the defense not only had to produce against the nation’s 31st most prolific scoring offense but had to do it against a formation it had not seen during film and practice preparation.

Tech coach Paul Johnson’s offense, with all its hitches and pitches and more options than a shopper has at Amazon.com, keeps defenses “running scared,” D’Onofrio said. Johnson had one more trick up his sleeve.

“They out-leveraged us with that formation,” D’Onofrio said. “It was a sign of them trying to beat us to the punch.”

UM struggled to adjust initially because the defense was constantly on the field. UM completed only six offensive plays in the first quarter while Tech built a 17-7 lead.

“They hit us fast,” Perryman said. “Against the option you’re running left to right, up and down the field. We kept telling each other, ‘Remain poised, calm down, we’ll figure it out and our offense will get going.’”

The confusion subsided at halftime, when D’Onofrio was able to meet with his players.

“You’re running out of the press box and into the elevator and down the hallway to the locker room,” he said. “You draw stuff up and you get three minutes to present it to the players. We were able to settle down, fight through it and execute well in the third and fourth quarters.”

After giving up 221 rushing yards in the first half, UM limited Tech to 114 in the second.

“It was our biggest growth game,” Chickillo said. “We had to adjust to something we hadn’t seen and fix what wasn’t working. They were killing us on some of those outside runs. I’d like to think we showed we’re a resilient group.”

The highlights included a fumble caused by Justin Renfro and recovered by Jimmy Gaines that squashed a Tech drive; a big third-down stop by Chickillo; an interception by Jenkins and a pick-six by Gunter; a hurry by Perryman and a sack by McCord. Perryman, Green and Gaines combined for 28 tackles.

Tag-team defense

Again, the hallmark of the defense was the depth and variety of its effort — and the lack of “freelancing” that Golden detests. A dozen players have made UM’s 18 sacks so far — already six more than all of last season. Six players have made eight interceptions. Seven players have forced a fumble. Eighteen different players have a tackle for loss. Golden calls it “tag-team defense.”

Now, if only the offense can correct its turnover problem.

But for the defense, the turnaround against Tech was reflective of its larger turnaround to earning a No. 14 national ranking.

“I take my hat off to Mark,” Golden said. “I’m proud of the way our guys fought. We learned a lot about our leadership.”